Several studies were performed using LANDSAT-4 and -5 simultaneous overpath data 40608-15472 and 50014-15465 over Pensacola, FL. The overlap region of these two scenes was determined visually on the IAT and then sampled into 32 x 32 segments. The mean and standard deviation (SD) for each segment were calculated. In general, the plots of the means of LANDSAT-4 versus LANDSAT-5 lie on the diagonal line. Some of the data lie out of the diagonal line, which indicates a possible bidirectional observation effect occurs. In addition to editing the five FCL files on CALDUMP tapes into seven 1000 minor frame (MF). CAL files, program LEE.FOR was modified to use information from start of shutter obscuration extracted from program START.FOR to create seven 200 MF.CAL files that can be run through the current TRAPP program for TM sensor characterization. The location of start of shutter obscuration was determined for both LANDSAT-4 and -5.